1944. On the Polish front, the fascists are building a secret defensive barrier. The task of obtaining the plans for the structures is assigned to a young intelligence agent, Maria, who must make contact with the frontline intelligence resident, Major Kurtz, behind enemy lines…

In the Crimea, on the shore of the Black Sea lives a girl nicknamed Dubravka. The girl plays soccer, swims in the sea, runs with boys in a race and often becomes a participant of any adventure. But the time comes - and Dubravka begins to grow up. She is as if in a “suspended” state: she is no longer interested in playing with boys, and older boys and girls do not pay much attention to her or perceive her as a child. In the house Dubravka settles vacationer Valentina Grigorievna. The girl likes her so much that Dubravka even “fell in love” with her. Dubravka's neighbor, the lonely father Peter Petrovich, and Valentina sympathize with each other, and Dubravka becomes very jealous of her. The girl does not know where to go from the contradictions simmering in her.